What is Newton's 3rd law of gravity?

Newton's third law (often called the law of action and reaction) states: For every action, there is an eual and opposite reaction. Applied to gravity, this means that if Earth pulls on you with a certain force, you pull on Earth with exactly the same force in the opposite direction. When you stand on the ground, Earth's gravity pulls you downward with your weight, and simultaneously, you pull Earth upward with an eual force. We don't notice Earth moving because its enormous mass makes the acceleration imperceptibly small, while your smaller mass results in a noticeable acceleration when you fall.